1. Field of the Invention
The present invention relates generally to a printed circuit board including an optical waveguide and a method of manufacturing the printed circuit board, and, more particularly, to a printed circuit board including an optical waveguide, which has a metal layer extending portion integrally connected to a metal layer constituting a mirror formed on the optical waveguide.
2. Description of the Related Art
In electronic elements, the development of existing printed circuit board technology employing copper-based electrical wiring has almost reached the limit of its ability to support increases in the speed of data processing as well as increased data capacity. Accordingly, as a technology for overcoming the problems occurring in copper-based electrical wiring, printed circuit boards that include optical wiring are receiving a lot of attention.
A printed circuit board including optical wiring, in which an optical waveguide capable of sending and receiving signals using light transmitted along polymer or optical fibers is incorporated, is referred to as an “EOCB (Electro-Optical Circuit Board). EOCBs are being extensively applied to backplanes and daughterboards used for communications in the aerospace industry and aviation electronics, base transceiver stations of UMTS (Universal Mobile telecommunication Systems), supercomputers, and the like.
In order to manufacture a printed circuit board including optical wiring, a mirror for diverting a light path must be provided in the printed circuit board.
FIGS. 1A to 1C and FIGS. 2A to 2C shows processes of forming a mirror in optical wiring according to conventional technologies.
FIGS. 1A to 1C are cross-sectional views showing the mechanical process of forming the mirror. As shown in FIG. 1A, a mirror notch 15 is formed in optical wiring 10 using a dicing blade 20. Thereafter, a gold (Au) layer is deposited on the mirror notch 15 through a mask 30 using a sputtering process, thus forming a mirror 50, as shown in FIG. 1B, or metal paste is charged in the mirror notch 15 through a mask 30 using a printing process, thus forming a mirror 60, as shown in FIG. 1C.
FIGS. 2A and 2C are cross-sectional views showing an optical process of forming a mirror. As shown in FIG. 2A, an excimer laser is radiated onto optical wiring 10 in the direction of an arrow, so as to form a mirror hole 17 therein. Thereafter, a gold (Au) layer is deposited on the inner wall of the mirror hole 17 through a mask 30 using a sputtering process, thus forming a mirror 55, as shown in FIG. 2B, or metal paste is charged in the mirror hole 17 through a mask 30 using a printing process, thus forming a mirror 65, as shown in FIG. 2C.
However, the conventional metal sputtering process has disadvantages in that, in the case of manufacturing an optical substrate having a large area, the amount of metal material consumed per unit coating area is relatively large, and in particular, the use of gold particles incurs high costs.
Similarly, the conventional printing process using metal paste also has disadvantages in that it fundamentally consumes a large amount of material and it is difficult to achieve even reflection on the boundary faces of the mirror. In order to assure even reflections on the boundary faces of the mirror, the metal paste must include a large amount of high reflective nanosized metal particles having uniform size distribution, thus causing an increase in the manufacturing costs.